Cylinder head assemblies for spark ignition internal combustion engines



June 25, 1963 A. c. SAMPIETRO 3, 7

CYLINDER HEAD ASSEMBLIES FOR SPARK IGNITION INTERNAL COMBUSTION ENGINES 4 Sheets-Sheet 1 Filed Nov. 7. 1960 June 25, 1963 A. c. SAMPIETRO 3, CYLINDER HEAD ASSEMBLIES FOR SPARK IGNITION INTERNAL COMBUSTION ENGINES Filed Nov. 7. 1960 4 She e ts-Sheet 2 51 r m A roe 52 i :9

ATTOQ VE) June 25, 1963 A. c. SAMPIETRO 3,094,977

CYLINDER HEAD ASSEMBLIES FOR SPARK IGNITION INTERNAL COMBUSTION ENGINES 4 Sheets-Sheet 3 Filed Nov. 7. 1960 zwy ATTOk/VEY June 25, 1963 A. SAMPIETRO 7 CYLINDER HEAD A MBLIES F0 0N INTERNAL I Flled Nov 7 1960 4 Sheets-Sheet 4 R SPARK IGNITI COMBUSTION ENGINES //WE/vroz Amen 9Q Patented June 25, 1963 3,094,977 CYLHNDER HEAD ASSEMBLIES FUR SPARK IGNI- TIGN INTERNAL CQMBUSTIQN ENGHIES Achilles C. Sampietro, 286 Puritan, Birmingham, Mich. Filed Nov. 7, 1960, Ser. No. 67,594 Claims. (Cl. 123-191) The present invention relates to spark ignition internal combustion engines having a cylinder block and a cylinder head assembly bolted or otherwise secured to the cylinder block, the cylinder head assembly including a cylinder head block formed with a separate combustion chamber for each cylinder of the engine. The invention relates more particularly to such engines having cylinder head assemblies of the type in which each combustion chamber is approximately part-spherical in shape and is fitted with one inlet valve, one exhaust valve, and at least one sparking plug. Such cylinder heads are generally known in the art as hemispherical and will be so referred to throughout the following specification and claims.

In the known cylinder head assemblies of this type in which the valves are actuated by rockers operated by a single overhead cam shaft, the two valves are arranged symmetrically on opposite sides of the combustion chamber and seat directly on the part-spherical Wall of the chamber, or on annular valve seats inset into the wall of the chamber.

This arrangement however has the disadvantage that, due to the relatively large size of the valves, the sparking plug cannot be set at the optimum position to provide maximum combustion efliciency and it is usually necessary to have two sparking plugs for each combustion chamber to provide an acceptable combustion efiiciency.

One object of the invention is to provide an improved arrangement of cylinder head assembly of the type described in which the sparking plug is located nearer to the optimum position for maximum combustion efiiciency than in previous known arrangements.

A further object of the invention is to provide an improved arrangement of valve actuating means for the cylinder head assembly of the type described.

According to the invention there is provided a-spark ignition internal combustion engine, a cylinder head assembly comprising a cylinder head block formed with a combustion chamber approximately part-spherical in shape, one inlet poppet valve and one exhaust poppet valve disposed on opposite sides of a central longitudinal plane .through said combustion chamber, each valve comprising a stem slidably mounted in a guide in the cylinder head block and a circular valve head disposed within the chamber, at least one of said valves being arranged with its axis offset from a central transverse plane through the chamber normal to said longitudinal plane, and the wall of the combustion chamber being formed with a pocket for the reception of the head of the offset valve, the wall of said pocket being a surface of revolution about the axis of the oifset valve, a spark plug mounted in said cylinder head block and projecting into the combustion chamber, and valve operating means including a single cam shaft mounted on the cylinder head block.

Embodiments of the invention will now be described by spherical wall 20 of the drawings in which:

FIG. 1 is a plan view of one arrangement of a cylinder head assembly according to the invention,

FIG. 2 is a view of the underside of part of the cylinder head block of the assembly, showing one of the combustion chambers,

FIG. 3 is a sectional view along the line A-A of FIG. 1,

FIG. 4 is a sectional view of another arrangement of a cylinder head assembly, and

FIG. 5 is .a plan view of a modified form of valve actuating mechanism for the cylinder head assembly according to the invention.

FIGS. 13 show a cylinder head assembly for a four cylinder engine and comprising a cyiinder head block it) secured by bolts 11 to the cylinder block of the engine, the cylinder head block it) being formed with four combustion chambers 12 each having an inlet port 13 communicating with an inlet duct 14 in the block it) and an exhaust port 15 communicating with an exhaust duct (not shown) in the block 10, an inlet poppet valve 16 and an exhaust poppet valve 17 for controlling flow of gas through the ports 13, 15 respectively in each chamber, a single overhead cam shaft 18 rotatably mounted in bearings (not shown) in the cylinder head block, and a separate rocker 19 for each of the valves.

Each combustion chamber 12 has a part-spherical Wall 20 formed with a pocket 21 in the portion of the wall surrounding the exhaust port 15, the wall of the pocket 21 also being part-spherical. As shown in FIG. 2, the inlet port 13 and the exhaust port 15 are arranged on opposite sides of a central longitudinal plane XX through the centre of the combustion chamber 12. The inlet port 13 is arranged with its axis in a central transverse plane Y-Y normal to the plane XX and aligned with the centre of curvature '22 (FIG. 3) of the partspherical wall of the chamber surrounding the port 13. The exhaust port 15 is smaller than the inlet port 13, and is arranged with its axis offset from but parallel to the plane YY and aligned with the centre of curvature 23 of the part-spherical Wall of the pocket 21. Further, as illustrated in FIG. 4, it will be noted that the inlet port 13 lies in a second plane 22a extending longitudinally of the combustion chamber and inclined to the central longitudinal plane XX and that the axis of the exhaust port 15 lies in a third plane 23a extending longitudinally of the combustion chamber and inclined to the central longitudinal plane XX on the opposite side thereof from the second plane 22a. Also, the three planes intersect in a common line which lies at the center 22 of the hemispherical combustion chamber.

As shown in FIG. 3, the inlet valve 16 comprises a cylindrical stem 24 slidably mounted in a guide 25 in the cylinder head block it and a circular head 26 co-axial with the stem and disposed within the combustion chamber. An annular collar 27 having a conical inner surface is mounted on a conical split collet 28 located in a recess v29 in the stem 24 and a coil spring 30 is compressed between the cylinder head block it and the collar 27, in the manner well known in the art. The inlet valve is arranged with its stem co-axial with the inlet port and aligned with the centre of curvature 22 of the partchamber 12, so that the valve spring 34} urges the circular head 26 into sealing engagement with the wall 20.

The exhaust valve 17 comprises a stem 31, a circular head 32, .a compression spring 33 and a collar mounted on the stem 32 by a split collet, the spring, collar and collet being constructed and arranged similar to that of the inlet valve. The exhaust valve is arranged with its stem coaxial with the exhaust port and aligned with the centre of curvature 23 of the part-spherical wall of the pocket 21 surrounding the exhaust port, so that the valve spring 33 urges the circular head 32 of the exhaust valve into sealing engagement with the wall of the pocket 21.

As shown in FIG. 4, each combustion chamber may be provided with an annular valve seat 34 inset into the wall 20 surrounding the inlet port, and an annular valve seat 35 inset into the wall of the pocket 121 surrounding the exhaust port, the heads 26, 32 of the two valves seating directly on the valve seats 34, 35 respectively.

A sparking plug 40 is provided for each of the combustion chambers 12, each plug being mounted in a screw-threaded aperture 41 in the cylinder head block and projecting into the combustion chamber. As shown in FIG. 1 each plug is mounted alongside the offset exhaust valve of the associated combustion chamber, so that the plug is thus positioned with its electrodes nearer to the centre of the combustion chamber, that is nearer to the optimum position for maximum combustion efficiency, than would be the case if the valves were arranged symmetrically with respect to the combustion chamber with the plug positioned equidistant from the two valves.

In the arrangement shown in FIGS. 1-3, the circular head 32 of the exhaust valve is located in a part-spherical pocket 21 and seats directly on the wall of the pocket. The wall of the pocket may however be any surface of revolution, for example, a conical surface, around the axis of the exhaust port. The pocket can thus easily be produced in a part-spherical wall of a combustion chamber by means of a rotary tool inserted through the exhaust port.

In the arrangement shown in FIGS. 1-3 only the exhaust port and valve are offset. The inlet port and valve may however also be offset from the plane YY and located in a further pocket having a wall which is a surface of revolution about the common axis of the inlet port and inlet valve.

Each rocker 19 is fulcrumed on a part-spherical seat 45 formed on the lower end of a sleeve 46 mounted on a stud 4-7 projecting upwardly between the cam shaft 18 and the stern of the associated valve. The lower end of the stud 4-7 is formed with splines 48 and is a force fit in an aperture 4% in the cylinder head block, the splines 48 deforming the wall of the aperture '49 and thereby preventing angular or axial movement of the stud under the forces exerted on the stud during operation of the rocker. The upper end of the stud 47 extends through an aperture 50 in a guide plate 51 which rests on the upper end of the sleeve 46, the upper end of the stud and the aperture 51} having co-operating flats (not shown) preventing angular movement of the guide plate on the stud, and an adjusting nut 52 is screwed on the upper end of the stud.

Each rocker 19 is made of sheet metal and comprises a dished member having a base 55 and two side walls 56. The centre of the base 55 is formed with a part-spherical portion 57 which is a close fit around the seat 45 on sleeve '46, the portion 57 having an aperture 59 for the passage of the stud 4-7, and the side walls project above the guide plate 51 which prevents angular movement of the rocker about the axis of the stud. One end of the rocker engages the upper surface of a cam 58 on the cam shaft 13 and the other end of the rocker engages the top end of the stem of the associated valve, the ends of the rocker being curved to provide line contact between the rocker and both the cam 58 and the stem of the valve.

The nut 52 in the stud is adjusted to provide a small clearance between the part-spherical seat 45 and the partspherical portion 57 on the rocker when the valve is closed, and on engagement of the lobe of the cam with the rocker, the rocker is initially raised until the partspherical portion 57 is engaged with the seat and then the rocker is swivelled about the seat 45 and depresses the valve stem.

FIG. 4 shows a cylinder head assembly having a combustion chamber 12, inlet and outlet ports 13, 15, inlet, and exhaust valves 16, 17 seating on valve seats 34, 35 respectively inset into the wall of the combustion chamber, and a single overhead cam shaft 18, all as previously described. The rocker support means of FIG. 4 however comprises a bracket 60 mounted on the cylinder head block and extending across the cam shaft, and a stud 61 for each of the rockers 19". Each stud 61 is mounted in a screw-threaded aperture 62 in the bracket 60 and extends downwardly and inwardly between the cam shaft and the associated valve stem, the lower end of the stud 61 being hemispherical and forming a seat 63 for the rocker 19'. Each rocker 19' is similar in construction to the rocker 19 of FIGS. 1-3, and comprises a base having a part-spherical portion 57' which is a close fit around the seat 63, and side walls 56' which extend upwardly and engage the sides of a guide element 64 which projects downwardly from the bracket and which prevents angular movement of the rocker 19' about the axis of the stud 61. One end of the base 55 of the rocker 19 engages the cam 58 and the other end engages the top of the stern of the associated valve, and the clearance between the seat 63 and the part-spherical portion '57 of the rocker 19', when the valve is closed, is regulated by angular adjustment of the stud 61 in the screw-threaded aperture 62. The stud is locked in position by a lock nut 65 on the screw-threaded end of the stud. The cylinder head assembly of FIG. 4 is particularly suitable for use in engines in which the rockers are subjected to heavy loading due to large valves, high speeds, or large offset of the valves.

in FIGS. 1-4 the two rockers for each combustion chamber are arranged normal to the axis of the cam shaft, and since the exhaust valve is offset, the two rockers are staggered along the cylinder head assembly. The two rockers are however both operated by a single cam of a length sufiicient to engage the adjacent ends of the rockers, and the direction of rotation of the cam shaft is controlled by the arrangement of the inlet and exhaust ports on opposite sides of the engine. For example, if the inlet ports are on the right hand side of the cylinder head assembly and the exhaust ports are on the left hand side, the direction of rotation of the cam shaft must be clockwise in order to obtain the correct sequence of operation of the inlet and exhaust valves.

In V engines having two banks of cylinders, the inlet ports are preferably arranged on the adjacent sides of the two banks and the exhaust ports on the outsides of the two banks, and if the cylinder head assembly for each bank comprises a single cam shaft having one cam for each cylinder, the two cam shafts must rotate in opposite directions. The two cam shafts of such V engines are however usually driven from a single driving member, and to avoid the provision of reversing gearing, the two cam shafts are preferably driven in the same direction with each valve operated by a single cam.

The cylinder head assembly of the present invention has the advantage that, since the exhaust valve is offset to one side of the central transverse plane through the combustion chamber, the two rockers for each chamber are olfset with respect to one another and, as shown in FIG. 5, can conveniently be modified to engage separate cams on the cam shaft. In FIG. 5 the rocker 19 for the exhaust valve has its end adjacent the cam shaft offset in the direction of offset of the exhaust port, and the rocker 19" for the inlet valve has its end adjacent the cam shaft offset in the opposite direction. The two rockers 19" are thus spaced apart a sufiicient distance along the length of the cylinder head assembly to enable each rocker to engage a separate cam 58' shaft.

The rockers of cylinder head assemblies for single bank in-line engines may of course be offset and engage separate cams, as shown in FIG. 5, in order to provide more freedom in the selection of timing values for the inlet and exhaust valves.

1 claim:

1. In a spark ignition internal combustion engine, the combination comprising: a cylinder head assembly ineluding a cylinder head block having at least one hemispherical combustion chamber the center of which lies on the axis of the cylinder; inlet and exhaust ports opening into said chamber on opposite sides of a central longitudinal plane through the chamber and so disposed that the axis of the inlet port lies in a second plane extending longitudinally of the combustion chamber and inclined to said central longitudinal plane and the axis of the exhaust port lies in a third plane extending longitudinally of the combustion chamber and inclined to said central longitudinal plane on the opposite side thereof from said second plane, the three planes intersecting in a common line on which lies the center of the hemispherical combustion chamber; inlet and exhaust poppet valve means controlling the flow of gas through said inlet and exhaust ports respectively, the axis of each of said valve means being coincident with the axis of the corresponding port and each of said valve means including a stem, a valve head carried by said stem, said head being located within the said chamber, and a valve seat formed in a Wall of said chamber; guide means in said head block slidably receiving said valve stems; at least one of said valve means being arranged with its axis in a plane parallel to and olfset from a central transverse plane through the chamber normal to the central longitudinal plane; means defining a pocket in the wall of said combustion chamber, the valve seat for said olfset valve being located in said pocket and the surface of said seat being a surface of revolution about the axis of the oltset valve; a spark plug mounted in said cylinder head block and projecting into said combustion chamber, the electrodes of said spark plug being near the central vertical axis of the combustion chamber; and valveoperating means including a single cam shaft mounted on the cylinder head block and having a separate rocker for operating each of said valves, a separate support for each of said rockers, said supports being elongated members arranged to support the rockers while suffering substantially only longitudinal stresses.

2. In a spark ignition internal combustion engine, a cylinder head assembly according to claim 1, wherein each said rocker is formed of sheet metal and comprises a base formed with a recess, and two side walls projecting from said base, said rocker being engaged on one of said rocker supports by said recess, and wherein each of said rocker supports includes a guide member, said guide member being disposed between said side Walls of the corresponding rocker to keep the rocker correctly located on its support.

3. In a spark ignition internal combustion engine, a cylinder head assembly as claimed in claim 1, wherein said pocket accommodating said offset valve forms part of a conical surface.

4. 'In a spark ignition internal combustion engine, a cylinder head assembly comprising: a cylinder head block formed with a hemispherical combustion chamber the center of which lies on the axis of the cylinder; inlet and exhaust ports opening into said chamber on opposite sides of a central longitudinal plane through the combustion chamber and so disposed that the axis of the inlet port lies in a second plane extending longitudinally of the combustion chamber and inclined to said central longitudinal plane and the axis of the exhaust port lies in a third plane extending longitudinally of the combustion chamber and inclined to said central longitudinal plane on the opposite side thereof from said on the cam second plane, the three planes intersecting in a common line on which lies the center of the hemispherical comlbustion chamber, inlet and exhaust poppet valve means controlling flow of gas through said ports the axis of each or" said valve means being coincident with the axis of the corresponding port and each valve means including a stem, a circular valve head carried by said stem and located within the chamber and a valve seat formed in a Wall of said chamber, at least one of said valve means being arranged with its axis in a plane parallel to and offset from a central transverse plane through the chamber normal to said longitudinal plane; means defining a pocket in the wall of said combustion chambeer to receive the head of the oifset valve means, the Wall of said pocket in the region surrounding the port associated with the oifset valve being a surface of revolution about the axis of the offset valve; a spark plug mounted in said cylinder head block and projecting into the combustion chamber, the electrodes of said spark plug being near the central vertical axis of the chamber; a single cam shaft mounted on the cylinder head block; rocker support means; each said rocker support means including a stud having one end thereof secured to the cylinder head block, a collar secured on the stud, the end of the collar adjacent the cylinder head block being part-spherical and forming a seat for the associated rocker, and each of said rockers being a sheet metal dished member having a part-spherical portion engaged with said seat, one end of said dished member being engaged with a cam on the cam shaft, the other end of said dished member being engaged with the stem of a valve.

5. In a spark ignition internal combustion engine, a cylinder head assembly comprising: a cylinder head block formed with a hemispherical combustion chamber the center of which lies on the axis of the cylinder; inlet and exhaust ports opening into said chamber on opposite sides of a central longitudinal plane through the combustion chamber and so disposed that the axis of the inlet port lies in a second plane extending longitudinally of the combustion chamber and inclined to said central longitudinal plane and the axis of the exhaust port lies in a third plane extending longitudinally of the combustion chamber and inclined to said central longitudinal plane on the opposite side thereof from said second plane, the three planes intersecting in a common line on which lies the center of the hemispherical combustion chamber; inlet and exhaust poppet valve means, controlling the flow of gas through said inlet and exhaust ports respectively, the axis of each of said valve means being coincident with the axis of the corresponding port and each including a stem, a circular valve head carried by said stem and located within said chamber, and a valve seat formed in a wall of said chamber, at least one of said valves being arranged with its axis in a plane parallel to and offset from a central transverse plane through the chamber normal to said longitudinal plane; means defining a pocket in the wall of said conrbustion chamber for receiving the head of the offset valve, means, the Wall of said pocket in the region surrounding the port associated With the offset valve means being a surface of revolution about the axis of the olfset valve means; a spark plug mounted in said cylinder head block and projecting into the combustion chamher, the electrodes of said valve being located near the central vertical axis of the chamber; a single cam shaft mounted on the cylinder head block; a mounting member rigidly secured above the cylinder head block; support studs secured to said mounting member and projecting towards the cylinder head block, each stud having a part-spherical seating formed on the end of the stud nearer the cylinder head block; sheet metal rockers each comprising a dished member having a part-spherical portion, said part-spherical portion of each stud being seated on the part-spherical seating of the associated stud, one end of said rocker being engaged with a cam on the cam References Cited in the file of this patent UNITED STATES PATENTS Pescara Dec. 29, 1942 De Pew Aug. 26, 1947 Marchal et a1. Feb. 23, 1954 Links et a1. Aug. 7, 1956 8 Nallinger Aug. 7, 1956 Boghossian Oct. 23, 11956 Sampietro Dec. 3, 1957 Leach Sept. 1, 1959 Lampredi Sept. 27, 1960 Fedak Oct. 11, 1960 Carpentier et a1 Oct. 25, 1960 Streit et a1. Jan. 16, 1962 

1. IN A SPARK IGNITION INTERNAL COMBUSTION ENGINE, THE COMBINATION COMPRISING: A CYLINDER HEAD ASSEMBLY INCLUDING A CYLINDER HEAD BLOCK HAVING AT LEAST ONE HEMISPHERICAL COMBUSTION CHAMBER THE CENTER OF WHICH LIES ON THE AXIS OF THE CYLIDNER; INLET AND EXHAUST PORTS OPENING INTO SAID CHAMBER ON OPPOSITE SIDES OF A CENTRAL LONGITUDINAL PLANE THROUGH THE CHAMBER AND SO DISPOSED THAT THE AXIS OF THE INLET PORT LIES IN A SECOND PLANE EXTENDING LONGITUDINALLY OF THE COMBUSTION CHAMBER AND INCLINED TO SAID CENTRAL LONGITUDINAL PLANE AND THE AXIS OF THE EXHAUST PORT LIES IN A THIRD PLANE EXTENDING LONGITUDINALLY OF THE COMBUSTION CHAMBER AND INCLINED TO SAID CENTRAL LONGITUDINAL PLANE ON THE OPPOSITE SIDE THEREOF FROM SAID SECOND PLANE, THE THREE PLANES INTERSECTING IN A COMMON LINE ON WHICH LIES THE CENTER OF THE HEMISPHERICAL COMBUSTION CHAMBER; INLET AND EXHAUST POPPET VALVE MEANS CONTROLLING THE FLOW OF GAS THROUGH SAID INLET AND EXHAUST PORTS RESPECTIVELY, THE AXIS OF EACH OF SAID VALVE MEANS BEING COINCIDENT WITH THE AXIS OF THE CORRESPONDING PORT AND EACH OF SAID VALVE MEANS INCLUDING A STEM, A VALVE HEAD CARRIED BY SAID STEM, SAID HEAD BEING LOCATED WITHIN THE SAID CHAMBER; GUIDE MEANS IN SEAT FORMED IN A WALL OF SAID CHAMBER; GUIDE MEANS IN SAID HEAD BLOCK SLIDABLY RECEIVING SAID VALVE STEMS; AT LEAST ONE OF SAID VALVE MEANS BEING ARRANGED WITH ITS AXIS IN A PLANE PARALLEL TO AND OFFSET FROM A CENTRAL TRANSVERSE PLANE THROUGH THE CHAMBER NORMAL TO THE CENTRAL LONGITUDINAL PLANE; MEANS DEFINING A POCKET IN THE WALL OF SAID COMBUSTION CHAMBER, THE VALVE SEAT FOR SAID OFFSET VALVE BEING LOCATED IN SAID POCKET AND THE SURFACE OF SAID SEAT BEING A SURFACE OF REVOLUTION ABOUT THE AXIS OF THE OFFSET VALVE; A SPARK PLUG MOUNTED IN SAID CYLINDER HEAD BLOCK AND PROJECTING INTO SAID COMBUSTION CHAMBER, THE ELECTRODES OF SAID SPARK PLUG BEING NEAR THE CENTRAL VERTICAL AXIS OF THE COMBUSTION CHAMBER; AND VALVEOPERATING MEANS INCLUDING A SINGLE CAM SHAFT MOUNTED ON THE CYLINDER HEAD BLOCK AND HAVING A SEPARATE ROCKER FOR OPERATING EACH OF SAID VALVES, A SEPARATE SUPPORT FOR EACH OF SAID ROCKERS, SAID SUPPORTS BEING ELONGATED MEMBERS ARRANGED TO SUPPORT THE ROCKERS WHILE SUFFERING SUBSTANTIALLY ONLY LONGITUDINAL STRESSES. 